Abstract: A method of surface hardening cobalt-chromium based orthopedic implant devices, and a cobalt-chromium orthopedic implant device prepared by the disclosed method. An orthopedic implant device made of a cobalt-chromium or cobalt-chromium-molybdenum alloy, such as ASTM F-75 or ASTM F-799 is exposed to molecular nitrogen gas or ionized nitrogen at a process temperature and for a process time duration sufficient to enhance surface hardness and wear resistance properties, without the formation of a measurable nitrogen layer that tends to increase surface roughness and brittleness and diminish wear resistance properties. The process temperature is in the range of 500.degree. F. to 2400.degree. F., preferably about 1400.degree. F., and the process time duration at the preferred process temperature is approximately 48 hours.
Type:
Grant
Filed:
March 15, 1993
Date of Patent:
May 3, 1994
Assignee:
Zimmer, Inc.
Inventors:
H. Ravindranath Shetty, Walter H. Ottersberg
Abstract: A method is taught for protecting fuel contacting surfaces of a gas turbine engine from carbon deposition by heating the element in a nitrogen containing atmosphere for sufficient time to cause penetration and absorption of nitrogen into the grain boundaries of the alloy surface, which acts as a barrier between the hydrocarbon fuel and the catalytic elements in the surfaces. The method includes heating at a temperature of 1800-1850 F. for about one hour, cooling to 1525-1575 F. and holding for about four hours, and cooling to a temperature of 1375-1425 F. and holding for about 16 hours.
Type:
Grant
Filed:
December 20, 1991
Date of Patent:
March 29, 1994
Assignee:
United Technologies Corporation
Inventors:
William H. Edwards, III, John A. Harris, III, Edward S. Smith
Abstract: A process for producing low-cost furnace atmospheres suitable for annealing and heat treating ferrous and non-ferrous metals and alloys, brazing metals and ceramics, sealing glass to metals, and sintering non-ferrous metal and ceramic powders from non-cryogenically produced nitrogen containing from 0.05 to 5.0% residual oxygen is presented. The disclosed process involves 1) mixing non-cryogenically produced nitrogen with a predetermined amount of dissociated ammonia, 2) passing the mixture through a low-pressure drop catalytic reactor, 3) converting the residual oxygen to an acceptable form such as moisture and reducing the residual oxygen level to below about 10 ppm, and 4) using the resultant gaseous mixture for annealing and heat treating ferrous and non-ferrous metals and alloys, brazing metals and ceramics, sealing glass to metals, and sintering non-ferrous metal and ceramic powders.
Type:
Grant
Filed:
December 22, 1992
Date of Patent:
March 1, 1994
Assignee:
Air Products and Chemicals, Inc.
Inventors:
Diwakar Garg, Paul T. Kilhefner, Donald P. Eichelberger, Brian B. Bonner
Abstract: Hyper-eutectic aluminum-silicon alloys are surface treated with nitrogen and carbon by ion implantation means so as to form hard, wear resistant particles of silicon nitride and silicon carbide which are surrounded by a hard matrix of aluminum nitride and aluminum carbide, depending on the species implanted. During applications where wear resistance is required, the hard silicon-based particles provide the wear resistant phase, thereby shielding the surrounding aluminum-based matrix. Yet the modified aluminum-based matrix is also sufficiently hard so as to provide strength and support for the silicon-based particles. Substantial improvements in wear resistance are obtained for these hyper-eutectic aluminum-silicon alloys, as compared to conventional alloys which have not been treated in accordance with this invention.
Type:
Grant
Filed:
December 19, 1991
Date of Patent:
December 21, 1993
Assignee:
General Motors Corporation
Inventors:
Aboud H. Hamdi, Gerard W. Malaczynski, Alaa A. Elmoursi
Abstract: Elements for use as protecting fuel contacting surfaces of a gas turbine engine are protected from carbon deposition by heating the element in a nitrogen containing atmosphere for sufficient time to cause penetration and absorption of nitrogen into the grain boundaries of the alloy surface, which acts as a barrier between the hydrocarbon fuel and the catalytic elements in the surfaces.
Type:
Grant
Filed:
December 20, 1991
Date of Patent:
October 19, 1993
Assignee:
United Techynologies Corporation
Inventors:
John A. Harris, III, William H. Edwards, III, Edward S. Smith
Abstract: A composite copper alloy having a modified surface is provided. An element or combination of elements both soluble in copper and reactive with nitrogen are cast with copper or a copper alloy forming a solid state solution. The alloy is reacted with a nitride former to modify the surface. A continuous surface film is formed by heating in a nitrogen containing gas. A dispersion of nitride precipitate in a copper matrix is formed by implanting nitrogen ions.
Abstract: This invention makes a furnace body divide into two, a pretreating chamber and a nitriding chamber by an opening and closing center wall. After pretreating works to be treated in the pretreating chamber, the opening and closing center wall is opened and the pretreated works are transferred to the nitriding chamber to nitride them. Treatment gas can be saved largely compared with the case that the nitriding is conducted after pretreating works in a furnace which has only a nitriding chamber.